In the management of industrial processes, it is crucial to have an accurate and fast insight into the measurement data generated by the sensors. The sensors do not have a display, they only detected certain physical quantities. Therefore, various local displays are in use, among which LED displays for installation in the loop are one of the most popular choices. In this article, we will explore the importance of a loop-fed display and an example of its use.
The loop-powered display is intended for local display of process parameters such as humidity, temperature, pressure, flow, length, etc. whereby converters with an analog output of 4 … 20 mA are used as sensors.
Loop power means that the display is powered directly from the 4 … 20 mA loop, which eliminates the need for an additional display power supply. This simplifies its installation while reducing process costs and increasing user efficiency.
Example: A pressure transducer with a measuring range of 0 … 10 bar is installed in a pipeline. The signal generated by the converter is sent to a control system a few meters or a few tens/hundred meters away. Perhaps the display is even part of the sensor design, but it is mounted in such a way that we cannot see the display, which is quite common. It is also common for the built-in display to be small and difficult to see/read.
Thus, the process operator does not see and does not know the current value of the pressure measurement, which makes it difficult to monitor the process and take appropriate measures. What good is measuring equipment if you can’t see what it’s measuring? Therefore, in such and similar cases, we use a local loop-powered display. Only this allows the operator to immediately display the pressure value, which enables control, setting, and adjustment of the process operation and quick action. This makes the operators more efficient at work because they have the measuring points under control. Not only through a remote control system but also visually and instantly.
In addition, the local display also benefits the maintenance team, allowing them to avoid dangerous tampering with devices under pressure or at high temperatures. At the same time, installation of the display is simple and fast and does not require an additional power source, as it is powered from a 4 … 20 mA loop.
The display is universal, which means that the user adjusts the display to a specific parameter. The applicability of the loop-powered display is wide and appears in various industrial sectors, from the food industry to the steel industry.
If we want our operators/technologists/maintainers to react quickly to the measurements and control them, they must have direct insight into the values detected by the sensors. Users spend a lot of time moving between the sensor installation site and the control room. By installing local displays that enable loop power, we save valuable time and enable quick action in case of deviations, maintenance, or emergency situations.
There is a wide range of LED displays available on the market, which differ in terms of their technical characteristics and functionality. Among them are LED-W11, SWE-N55L, and DIH50/DIH52 indicators or displays.
INOR’s legendary LED-W11 is still on sale while supplies last and will get its successor at the end of 2023 after more than twenty years.
The sales program also includes Simex’s SWE-N55L and Wika DIH50/DIH52 display for current loops with HART® WIKA communication, which also provides easy installation and use and flexible display for various parameters.
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For opinions and explanations, they are always available:
expert in temperature measurements: Aleksandra Lepenik
measurement expert: Zoran Lepenik
Mojca Kugler and Aleksandra Lepenik, June 2023
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